There is a trend within the field of portable communicating devices, and especially within the field of cellular phones to have the antenna built into the phone itself. At the same time, there is often a need for several frequency bands for such phones. There are several reasons for providing different frequency bands. First, some networks provide several frequency bands in order to better distribute traffic in the network. For example, GSM provides two separate bands that can be used. There are also different types of networks in different countries that use different frequency bands.
It is not a simple task to provide an antenna arrangement that can be used with good efficiency in several bands, especially if the antenna is to be based on a Planar Inverted F Antenna (PIFA) antenna and perhaps provided in a small phone.
Various methods have been developed to achieve the additional bandwidth such as using parasitic elements that can be end coupled or side coupled.
When providing such an antenna arrangement, there is in addition often a requirement to keep the antenna arrangement as small as possible. This is not a simple task to obtain when it is at the same time desired to provide several frequency bands. Since the antenna is to be small, there is furthermore a need to use the antenna volume as efficiently as possible.